1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) panel transferring system and a method thereof, and particularly, to a liquid crystal display panel system and a method thereof capable of preventing fabrication of a defective LCD panel when separating and taking out a LCD panel from a substrate by accurately aligning the LCD panel in a panel transferring apparatus using a camera installed at the panel transferring apparatus for recognizing an alignment mark.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) device provides liquid crystal cells arranged in a matrix form with corresponding data signals according to image information in order to display a desired image by controlling light-transmittance of each liquid crystal cell.
Accordingly, the LCD device includes a LCD panel where the liquid crystal cells are arranged in a matrix form and a driver integrated circuit (IC) for driving the liquid crystal cells of the LCD panel.
The LCD panel includes a color filter substrate and a thin film transistor array substrate wherein the color filter substrate and the transistor array substrate face each other and a liquid crystal layer formed therebetween.
On the thin film transistor array substrate of the LCD panel a plurality of data lines transmitting data signals supplied from the data driver integrated circuit to the liquid crystal cells are arranged. A plurality of gate lines for transmitting scan signals supplied from a gate driver integrated circuit to the liquid crystal cells are arranged perpendicular to the data lines on the thin film transistor array substrate. The liquid crystal cells are arranged at intersections of the data lines and the gate lines.
The gate driver integrated circuit supplies the scan signals to the plurality of gate lines sequentially so that the liquid crystal cells arranged in a matrix form can be sequentially selected one line by one line. The data signals are supplied to the liquid crystal cells of each sequentially selected line from the data driver integrated circuit through the plurality of data lines.
A common electrode and a pixel electrode are respectively formed at the inner sides of the color filter substrate and the thin film transistor array substrate, thereby applying an electric field to the liquid crystal layer. Whereas the pixel electrode is formed correspondingly to each liquid crystal cell on the thin film transistor array substrate, the common electrode is formed integrally on an entire surface of the color filter substrate. Accordingly, light-transmittance of the liquid crystal cells may be separately controlled by controlling a first voltage applied to the pixel electrode while applying a second voltage to the common electrode.
A thin film transistor is formed at the respective liquid crystal cells for use as a switching device for controlling the voltage applied to the pixel electrode formed on each liquid crystal cell.
A plurality of thin film transistor array substrates are formed on a large mother substrate and a plurality of color filter substrates are formed on another mother substrate. The two mother substrates then are bonded, so that a plurality of LCD panels are formed at the same time to improve yield. A process for cutting the bonded substrates into unit LCD panels is then required.
Generally, the cutting process to produce unit LCD panels includes using a diamond wheel to form a scribing line at a surface of the mother substrate, the diamond wheel having hardness greater than that of glass, and breaking the mother substrate at the scribing line by applying a mechanical force thereto. Hereinafter, a LCD panel will be explained with reference to the FIGS. 1, 2, and 3.
FIG. 1 is a view showing a schematic planar structure of an exemplary unit LCD panel prepared by bonding a thin film transistor array substrate to a color filter substrate.
Referring to FIG. 1, the unit LCD panel 10 includes: an image display unit 13 having liquid crystal cells arranged in a matrix form; a gate pad unit 14 connected to gate lines of the image display unit 13; and a data pad unit 15 connected to data lines. The gate pad unit 14 and the data pad unit 15 are formed on edge areas of a thin film transistor array substrate 1 that do not overlap the color filter substrate 2. The gate pad unit 14 supplies each of the gate lines of the image display unit 13 with a corresponding scan signal supplied from a gate driver integrated circuit, and the data pad unit 15 provides the data lines with image information supplied from a data driver integrated circuit.
On the thin film transistor array substrate 1 of the image display unit 13, the data lines having the image information applied thereto are arranged to cross substantially perpendicularly the gate lines having the scan signals applied thereto. Thin film transistors are formed at each intersection of the scan and data lines to switch the liquid crystal cells. Pixel electrodes are connected to the thin film transistors to drive the liquid crystal cells. A passivation layer is formed over the entire surface to protect the electrodes and the thin film transistors.
Also, color filters separated by a black matrix for each cell area are formed on the color filter substrate 2 of the pixel display unit 13. A transparent common electrode is formed on the thin film transistor array substrate 1.
A cell gap is provided between the thin film transistor array substrate 1 and the color filter substrate 2, that are bonded to each other by sealant (not shown) formed at the peripheral regions of the image display unit 13. The cell gap maintains a space between the thin film transistor array substrate 1 and the color filter substrate 2. A liquid crystal layer (not shown) is formed in the space between the thin film transistor array substrate 1 and the color filter substrate 2.
FIG. 2 is a view showing an exemplary cross-sectional structure of a first mother substrate having thin film transistor array substrates 1 and a second mother substrate having color filter substrates 2, wherein the first and second mother substrates are bonded to each other to form a plurality of LCD panels.
Referring to FIG. 2, each unit LCD panel has the thin film transistor array substrate 1 longer than the color filter substrate 2. This is because the gate pad unit 14 and the data pad unit 15 are formed, as illustrated in FIG. 1, at the edges of the thin film transistor array substrate 1 that does not overlap the color filter substrate 2.
Hence, the second mother substrate 30 and the color filter substrates 2 formed thereon are spaced apart from each other by a dummy region 31 corresponding to the protruding area of each thin film transistor array substrate 1 on the first mother substrate 20.
Moreover, the unit LCD panels are arranged so as to maximize the use of the first and second mother substrates 20 and 30. Although it depends on models, the unit LCD panels are generally spaced apart from each other at a distance corresponding to the area of the other dummy region 32.
After the first mother substrate 20 having the thin film transistor array substrates 1 is bonded to the second mother substrate 30 having the color filter substrates 2, a scribing process and a breaking process are carried out to individually cut the LCD panels.
The scribing process is performed to form a scribing line using a cutting wheel, and the breaking process is performed to separate the substrates along the scribing line using a steam cutting device.
FIG. 3 illustrates a substrate 40 processed by the cutting wheel and the steam cutting device. As illustrated in FIG. 3, a scribing line 33 is formed on the substrate 40 including a plurality of LCD panels 10 using the cutting wheel, and the substrate 40 is completely cut along the scribing line 33 using the steam cutting device.
However, several problems may occur in the apparatus for cutting the substrate using the steam cutting device. In order to separate the LCD panel from the substrate after cutting by the steam cutting device, the cut dummy substrate must be lowered by gravity below the cut line. Accordingly, space must be provided below the cut line. Dust may be generated from the dummy substrate lowered below the cut line. In addition, if the substrate is not successfully cut using the steam cutting device, the uncut substrate is transferred to later processes, resulting in an interruption of the later processes.